The invention is based on a fuel injection apparatus which serves to inject a fuel mixture comprising a main fuel and at least one additional fluid or additional fuel.
For use in Diesel engines, a fuel mixture for instance comprising Diesel fuel and water, or Diesel fuel and alcohol, is supplied by the associated fuel injection pump. In known types of apparatus, mixing nozzles of appropriate embodiment are used in order to assure intimate mixing or emulsification of the two components of the fluid, or else the fuel is already delivered in the form of a mixture, via a mixing device, to the suction chamber of the fuel injection pump. Since under changing operating conditions the fuel mixture must be changed and adapted very rapidly, and it is also necessary to avoid separation of the fuel components as much as possible, injection apparatus is already known in which the fuel mixing is performed directly in the pump work chamber of the fuel injection pump during the intake stroke thereof. For instance, a fuel injection apparatus that is equipped with the characteristics set forth herein is known from Austrian Pat. No. 102,637 which is the same as British Pat. No. 230,496. A manually adjustable throttle valve inserted into the second inflow conduit for the additional fluid serves as a control device to adjust the mixture ratio. With this throttle valve, the mixture ratio of the fuel mixture aspirated during the intake stroke of the pump piston can be adjusted roughly; however, very precise adjustment of the mixture ratio cannot be attained with such a device, nor can a change be made in this mixture ratio that reacts very rapidly to changing operating conditions. In the exemplary embodiment shown in FIGS. 4 and 5, having two metering valves embodied as suction valves, the inflow of the two fluid components is effected via two chambers disposed preceding the pump work chamber; these chambers disadvantageously increase the idle volume in the pump work chamber. As a result, it is impossible to generate very high injection pressures, and the fuel metering precision is reduced. These disadvantages are also present in the other exemplary embodiments, shown in FIGS. 1-3 of Austrian Pat. No. 102 637, in each of which a chamber connected laterally to the pump work chamber is provided to receive the head of the suction valve that is moved during the intake stroke.